The subject matter disclosed herein relates to the art of water-from-air systems and, more particularly, a water-from-air system that employs a desiccant wheel.
Obtaining water from dry, arid, and/or desert regions is difficult. Typically, water is either found locally from a well or must be trucked in by tankers. In certain environments, obtaining well water is not an option or, if available, the water may contain contaminants that could be harmful to certain humans. In such cases, the water must be brought in by tanker trucks. The costs associated with transporting water are relatively high. Fuel costs, vehicle maintenance costs, and ensuring water quality all contribute to the overall cost of transporting water to remote locations. Alternatively, water can be extracted from air at the remote location. That is, in place of transporting water to the remote location, a water-from-air extraction system can be employed.
Certain water-from-air extraction systems, such as indicated at 2 in FIG. 1, employ a desiccant wheel 3 fluidly connected to an open air passage 4, and a closed air or extraction loop 6. Open air passage 4 carries process air, such as ambient air, exhaust air or the like from a process fan 8 to desiccant wheel 3. The process air then passes from desiccant wheel 3 back to ambient. In contrast, in closed air loop 6 the same air is re-circulated through desiccant wheel 3 to pick up moisture. More specifically, in the embodiment shown, saturated air flows from a regeneration fan 14 through a heater 16. The heater dries the air which then flows through desiccant wheel 3 to absorb moisture deposited by the process air. The moisture laden or saturated air passes from desiccant wheel 3 to a condenser 20. A fan directs an air flow across condenser 20 causing a portion of the moisture in the saturated air to condense and pass to a water storage area 24. With the portion of the moisture removed, the saturated air passes back to regeneration fan 14 and onto heater 16 to repeat the process.
While effective, closed loop systems require the use of an additional fan or air motive device to ensure air movement. In the above described system, fan 14 is exposed to saturated air or air having a very high moisture content. The high moisture content of the air creates certain maintenance issues. The moisture in the air has a detrimental effect on fan components such as bearings and electrical connections. Thus, the operational life of fans in a closed loops system is rather short. In addition, there are certain costs associated with driving the additional fan. For example, fuel to run generators that create the electricity to drive the various components of the water-from-air system must be transported out to the remote area.